Interpretive Summary: Poultry processors are required to produce safe food products, including removing any visible fecal material and, hopefully, reducing bacteria on raw chicken carcasses. Processors use a large, multi-nozzle water spray washer (called an inside-outside bird washer, or IOBW) after the chickens are eviscerated. Typically the IOBW does a good job but uses a large amount of water. An experiment was conducted to determine how well the IOBW washed off fecal material as determined by the number and incidence of bacteria, if removed feces would pass onto adjacent clean carcasses (cross-contamination) and if different water pressures affected the effectiveness of the machine. Visibly clean chicken carcasses and carcasses contaminated with a known amount of fecal material (including Salmonella and Campylobacter cultures) were passed through the IOBW. Two different water pressures (40 or 80 PSI) were used to determine if the washer could remove bacteria and use less water. Thirty six chicken carcasses were used, with 12 intentionally contaminated with feces, then 12 clean carcasses placed beside the contaminated carcasses. 12 more clean carcasses were used as controls. At commercial line speeds the IOBW did slightly reduce total bacteria and E. coli, but more importantly, the IOBW reduced both the number of pathogenic bacteria (Campylobacter and Salmonella) on carcasses as well as reduce the number of carcasses that contained pathogenic bacteria. The clean carcasses beside the contaminated carcasses were not affected, so cross-contamination in the IOBW was not observed. The IOBW was as effective at 40 PSI as at 80 PSI, so water savings could be realized by processors. Overall, the IOBW was effective at reducing bacteria, producing fewer carcasses with pathogenic bacteria, did not allow cross-contamination, and can operate at lower pressure to conserve water.

Technical Abstract:
Processors are washing carcasses with one or more inside-outside bird washers (IOBW) to comply with the zero tolerance for visible feces regulation mandated by the USDA Food Safety Inspection Service. A study was conducted to determine the effect of an IOBW on total aerobic bacteria, E. coli, Campylobacter, and Salmonella recovered from uncontaminated (control), contaminated, and possibly cross contaminated broiler carcasses at two different IOBW water pressure settings. In each of three trials, 12 commercially processed carcasses, consisting of two groups that each contained two control carcasses, two carcasses contaminated with 100 mg cecal contents (inoculated with Campylobacter and Salmonella), and two carcasses uncontaminated and placed adjacent to contaminated birds during washing (to determine cross contamination) were prepared (n=36). Whole carcass rinses were conducted on each carcass prior to contamination and washing, then repeated after washing. Carcasses were washed with an in-line commercial IOBW set at 140 birds per minute for a 5 sec dwell time and either 276 or 552 kPa (40 or 80 PSI) water pressure. Counts of total bacteria, E. coli, Campylobacter, or Salmonella were not significantly affected (P<0.05) by contamination with feces, by cross-contamination, or by IOBW pressure. The overall effect of washing was a slight but significant reduction in total aerobic bacteria (4.9 to 4.8) and E. coli (3.2 to 3.0) log cfu/ml rinsate. The IOBW decreased the incidence of Campylobacter from 22/36 positive carcasses (14 positive incoming carcasses plus 8 inoculated carcasses) to 1/36 positives, while Salmonella incidence decreased from 12/36 contaminated (inoculated) carcasses to 3/36 positive carcasses after washing. The IOBW removed carcass contamination to levels equivalent with uncontaminated controls without cross contaminating other carcasses. The incidence of Campylobacter was decreased, as was Salmonella to a lesser extent. Even smaller reductions were noted for total bacteria and E. coli.